1. Field of the Invention
The invention relates in general to a display device, and more particularly to an OLED display device having two substrates and a manufacturing method thereof.
2. Description of the Related Art
Organic light emitting diode (OLED) display devices can be divided into the bottom emission type, the top emission type and the inverted top emission type according to the light emitting direction and structure. The bottom emission type OLED display device includes a bottom substrate, an anode, an organic material layer, a cathode and a top substrate sequentially disposed. As the light emitted by the organic material layer of the bottom emission type OLED display device passes through the bottom substrate on which several thin film transistors are disposed, the aperture ratio of the bottom emission type OLED display device decreases due to the blockage of the thin film transistors.
To avoid the decrease in the aperture ratio, the top emission type OLED display device further includes a reflection layer disposed on the anode, and the cathode is made of a light-pervious material. Thus, the light emitted by the organic material layer of the top emission type OLED display device can be reflected by the reflection layer, so that the light is projected towards the top substrate in which no thin film transistor is disposed, hence avoiding the decrease in the aperture ratio. However, a cathode made of a light-pervious material often has an inferior electron injection effect which further affects the display effect.
In addition, the top emission type OLED display device is a cathode common structure, wherein the anode of the top emission type OLED display device is electrically connected to the thin film transistors. When the voltage applied to the cathode common OLED display device increases, the driving voltage of the thin film transistors is affected to become unstable. The inverted top emission type OLED display device is an anode common structure, wherein the cathode of the inverted top emission type OLED display device is electrically connected to the thin film transistors. The inverted top emission type OLED display device, being an anode common structure, can avoid the driving voltage of the thin film transistors being affected by the voltage applied to the OLED display device. However, the anode of the inverted top emission type OLED display device needs to be formed on the organic material layer by way of sputtering. As a result, the organic material layer may be sputtered and damaged during the manufacturing process, hence affecting the light emitting effect.